Device for the control of at least one gas exchange valve

ABSTRACT

A device is indicated for controlling at least one gas exchange valve for an combustion cylinder of an internal combustion engine, having an hydraulic actuator for valve actuation and having a high-pressure pump that supplies the actuator with a pressure medium. In order to reduce the production costs, the high-pressure pump is formed as a control-sleeve pump having a stroke-driven pump plunger that limits a pump chamber, and having a spool valve surrounding this plunger. In the pump plunger and spool valve, on the one hand a control groove that runs obliquely to the stroke direction is provided, and on the other hand a spill opening that cooperates therewith is provided, which together bring about a relief of pressure of the pump chamber when they overlap. For the controlling of the phase position and duration of the valve actuation, the pump plunger and the spool valve are able to be rotated relative to one another, and the spool valve is able to be displaced relative to the pump plunger.

FIELD OF THE INVENTION

The present invention is based on a device for controlling at least onegas exchange valve that is allocated to a combustion cylinder of aninternal combustion engine.

BACKGROUND INFORMATION

A known device of this type (German Published Patent Application No. 19826 047) has, as an actuator or valve positioner, a double-actinghydraulic working cylinder in which a control piston is guided so as tobe axially displaceable, this control piston being fixedly connectedwith the valve shaft of the gas exchange valve integrated in thecombustion cylinder, or itself forming the end thereof further away fromthe valve closing element. In the working cylinder, the control pistonlimits, with its two end surfaces facing away from one another, an upperand lower working chamber. While the lower working chamber, via which apiston displacement in the direction of valve closing is effected, isconstantly charged with a medium under high pressure, for examplehydraulic oil, the upper working chamber, via which a pistondisplacement in the direction of valve opening is effected, ispurposively charged with pressure medium that is under high pressure, oris again relieved of stress to approximately ambient pressure, with theaid of electric control valves, preferably 2/2-way magnetic valves. Thepressure medium under high pressure is supplied by a high-pressure pump.Of the control valves, a first control valve connects the first workingchamber with the high-pressure pump, and a second control valve connectsthe upper working chamber with a relief line that debouches into apressure medium reservoir. In the closed state of the gas exchangevalve, the upper working chamber is separated from the closed firstcontrol valve by the high-pressure pump, and is connected with therelief line via the opened second control valve, so that the controlpiston is guided into its closed position by the pressure of the mediumprevailing in the lower working chamber. For the opening of the gasexchange valve, the control valves are switched over, through which theupper working chamber is closed off from the relief line and isconnected to the high-pressure pump. Because the piston area of thecontrol piston in the upper working chamber is larger than the effectivesurface of the control piston in the lower working chamber, the controlpiston is displaced so as to open the gas exchange valve. The magnitudeof the opening stroke depends on the design of the electrical controlsignal applied to the first control valve, and the speed of openingdepends on the high pressure of the pressure medium, applied by thehigh-pressure pump.

From German Published Patent Application No. 30 14 028, a fuel injectionpump for internal combustion engines is known that has a pumping anddistribution plunger that simultaneously executes a back-and-forthstroke motion and a rotational motion. The pumping and distributionplunger, formed as a stepped piston, limits a pump chamber. In thejacket surface of the pumping and distribution plunger, there issituated a distribution longitudinal groove that is connected with thepump chamber and that, during rotation, successively activates pressurepassages that lead to pressure lines that are connected with theinternal combustion engine. The number of pressure passages correspondsto the number of combustion cylinders in the internal combustion enginethat are to be supplied. During the rotation of the pumping anddistribution plunger, the pressure passages that are not under highpressure are successively relieved of pressure, to a suction chamber,via one or more longitudinal grooves, an annular groove, and a reliefbore. The regulation of the injected fuel quantity takes place via aspool valve that is situated on the pumping and distribution plunger inaxially displaceable fashion and can be axially displaced by anhydraulic controller. The pumping chamber is connected, via bored holesin the pumping and distribution plunger, with longitudinal groovessituated on the jacket surface thereof that work together with anopening in the spool valve. As long as these bored holes are controlledto open by the molded opening via the longitudinal grooves, no injectiontakes place. However, as soon as these bored openings are blocked, andsimultaneously, during the pressure stroke of the pumping anddistribution plunger, the distribution longitudinal groove coincideswith one of the pressure passages, injection takes place. The injectedquantity is thus determined by the spacing of the longitudinal grooves,at least one of the longitudinal grooves being situated obliquely to theother, so that an axial displacement of the spool valve causes analteration of the activation distance, and thus of the injectedquantity.

Through further rotation of the spool valve, the beginning and end ofthe injection are simultaneously displaced.

What is known as a control-sleeve in-line fuel-injection pump is knownfor diesel engines (Bosch, “Automotive Handbook”, 23rd ed., ISBN3-528-03876-4, pp. 542 and 543), having, for each combustion cylinder ofthe diesel engine, a pump plunger that limits a pump chamber and isdriven by a cam and that has an oblique control groove that is connectedwith the pump working chamber, and what is known as a control sleevethat is provided with a spill port. A setting shaft having a pluralityof control-sleeve levers, of which each engages in a respective controlsleeve, moves all the control sleeves in common. An electromagneticactuator mechanism in turn rotates the setting shaft. According to theposition of the control sleeve, the delivery begins earlier or laterrelative to the actuating cam. The delivery end is achieved when thecontrol groove and the spill port coincide.

SUMMARY OF THE INVENTION

The device according to the present invention for controlling at leastone gas exchange valve allocated to a combustion cylinder of an internalcombustion engine has the advantage that through the combination of theproduction of pressure on the one hand and the controlling of theopening stroke and of the time of opening of the gas exchange valve inthe control-sleeve pump on the other hand, the outlay of control valvesand- control electronics, as well as functional software, is reduced.The control-sleeve pump used is a mature component that has proven itseffectiveness in fuel-injection systems for internal combustion engines,e.g. as an element of the control-sleeve in-line fuel-injection pumpdescribed above, and thus has low susceptibility to failure. Itsinstallation is simple. Through the savings of electrical controlvalves, the electronic outlay in the control apparatus is also reduced,and the energy consumption is lowered. Given a plurality of gas exchangevalves in the internal combustion engine, each having an associatedcontrol device, both the load control and the phase displacement of allthe gas exchange valves can be carried out through identical rotation ofthe pump plungers, or identical axial displacement of the spool valvesof all the control devices. A switching off of the valves or of thecylinders of the internal combustion engine can be realized usingadditional simple electrical control valves having a low switching timerequirement.

According to a preferred specific embodiment of the present invention,the control groove is incorporated into the jacket of the pump plunger,and is connected with the pump chamber via a connecting bore that runsin the pump plunger, while the spill opening in the spool valve isrealized in the form of a radial bore. Through axial displacement of thespool valve, the phase position of the opening of the gas exchangevalve, i.e., the time of opening relative to that of the other gasexchange valves, is adjusted, and through rotation of the pump plungerthe duration of the opening of the gas exchange valve is adjusted.

According to an advantageous specific embodiment of the presentinvention, a non-return valve is situated between the pump chamber andthe pump outlet, and a relief opening that can optionally be shut offusing an electrically controllable shutoff valve is connected to thepump outlet. The shutoff valve is preferably formed as a 2/2-waymagnetic valve having a spring return mechanism. In this way, theopening of the gas exchange valve can be executed with a variablestroke, the non-return valve connected before the pump outlet preventingan immediate intake of the gas exchange valve at the spill of thecontrol-sleeve pump, so that the instantaneous stroke of the gasexchange valve is maintained. The opening of the shutoff valve at thecorrect time triggers the closing process of the gas exchange valve bythe valve closing spring. Through these measures, a fully variable valvegear is achieved, with which, given a small load-of the gas exchangevalve, opening takes place only for an extremely short time, in order toadmit only a very small quantity of fresh gas into the combustioncylinder, in order to lower fuel consumption. Such an extremely shortopening of the gas exchange valve is possible only through asuperproportional reduction of the valve stroke. Through the constantholding open of the shutoff valve, the gas exchange valve can be keptconstantly closed, and a valve or cylinder shutting off can be realizedin the internal combustion engine.

If variable stroke control is omitted, in a simplified embodiment of thecontrol device according to the present invention, instead of thenon-return valve and electrically controlled shutoff valve a simplepressure limiter or overflow valve, which opens mechanically when thereis excess pressure, can be connected to the pump outlet of thecontrol-sleeve pump. This simplified and more economical version of thecontrol device can advantageously be used for the controlling of thedischarge valves, because here a variable opening stroke is of noparticular interest.

According to an advantageous specific embodiment of the presentinvention, given a plurality of gas exchange valves to each of which anactuator is allocated for valve actuation, the actuators for selectedgas exchange valves situated in different combustion cylinders can beconnected to a common control-sleeve pump, resulting in an additionalsavings of cost. Here, for each two actuators a switchover valve isprovided, such that one actuator is connected to each of the two valveoutlets thereof, and the valve input thereof, which can optionally beconnected with the valve outlets, is adjacent to the pump outlet of thecontrol-sleeve pump. The switchover valve is preferably fashioned as a3/2-way magnetic valve having a spring return mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a diagram of a device for controlling a gas exchange valve.

FIG. 2 shows an enlarged sectional view of a control-sleeve pump in thecontrol device according to FIG. 1.

FIG. 3 in the same representation as in FIG. 1, shows a simplifiedversion of the control device.

FIG. 4 shows a diagram of the control device for controlling gasexchange valves allocated to two different combustion cylinders.

DETAILED DESCRIPTION

The device shown in the diagram in FIG. 1 for controlling a gas exchangevalve 10 for a combustion cylinder—shown partially with its cylinderhead 11—of an internal combustion engine in motor vehicles has anhydraulic actuator 12 for valve actuation and a high-pressure pump,formed as a control-sleeve pump 13, that charges actuator 12 with amedium under high pressure, e.g. hydraulic oil.

Gas exchange valve 10, situated in cylinder head 11 of the combustioncylinder, can be an intake valve or an outlet valve. It has, in a knownmanner, a valve element 15 that closes a valve opening 14 and thatformed on a valve shaft 16 and cooperates with a valve seat 17surrounding valve opening 14.

Actuator 12 has a control piston 19 that is guided in displaceablefashion in a working cylinder 18, and that limits an hydraulic workingchamber 20 and is coupled with valve shaft 16 of gas exchange valve 10,and is fashioned in one piece with this shaft in the exemplaryembodiment. In order to open gas exchange valve 10, control piston 19 isdisplaced against the force of a valve closing spring 21 by medium thatis under high pressure and that is introduced into hydraulic workingchamber 20 by control-sleeve pump 13.

Control-sleeve pump 13 has a pump plunger 22 that limits, in a pumpcylinder 23, a pump chamber 24, and is driven to execute a stroke motionby a carn 26 that is situated in rotationally rigid fashion on acamshaft 25, when camshaft 25 rotates. As can be seen more clearly inthe enlarged view of control-sleeve pump 13 in FIG. 2, in the jacket ofpump plunger 22 there is incorporated a control groove 27 that runsobliquely to the stroke direction of pump plunger 22, i.e., at an acuteangle to the pump plunger axis, and that is connected with pump chamber24 via a blind bored hole 28 situated axially in pump plunger 22, in aconnection that permits the exchange of pressure medium. Control-sleevepump 13 additionally has a spool valve 29 that surrounds pump plunger22. In spool valve 29, a spill opening 30 is made in the form of aradial bore, shown in FIG. 2 in broken lines, because in the sectionalrepresentation it is situated in the cut-away half of annular spoolvalve 29. If, during the stroke of pump plunger 22, control groove 27and spill opening 30 overlap, pressure medium can flow out of pumpchamber 24, which relieves pump chamber 24 of pressure. As is indicatedsymbolically by arrow 33, spool valve 29 can be displaced axially onpump plunger 22, for which purpose an actuating lever 31 of a controllerengages in a guide groove 32 on the outer periphery of spool valve 29.As is indicated by arrow 34 in FIG. 2, pump plunger 20 is fashioned soas to be able to be rotated about its axis. For the rotation of pumpplunger 22, an actuating element (not shown) engages thereon. Throughthis rotational adjustment of pump plunger 22, the duration of openingof gas exchange valve 10 is altered, while through displacement of spoolvalve 29 it is possible to influence the phase position of the openingof gas exchange valve 10, i.e., the time at which gas exchange valve 10is opened relative to a reference time.

Pump chamber 24 is connected with a pump inlet 36 via a pump inlet valve35, formed as a non-return valve, and is connected with a pump outlet 38via a non-return valve 37 whose blocking direction is oriented towardspump chamber 24. Pump inlet 36 is connected to a pressure mediumreservoir 39, and pump outlet 38 is connected to hydraulic workingchamber 20 of actuator 12.

For the controlling of a variable stroke of gas exchange valve 10 forthe purpose of achieving an extremely short opening duration of the gasexchange valve in partial load and low load operation of the internalcombustion engine, there is connected to pump outlet 38 an additionalrelief opening that can be optionally closed by an electricallycontrollable closing valve 40. In the exemplary embodiment shown in FIG.1, the relief opening is connected with a return line 41 that leads topressure medium reservoir 39, and a 2/2-way magnetic valve 42 having aspring return mechanism is used as shutoff valve 40. This magnetic valve42 is for example formed so as to be open without current, and, for anopening stroke of gas exchange valve 10 that is to be introduced, is ledinto its closed position by a control device (not shown), by beingsupplied with current. If, during the activation process of gas exchangevalve 10, the current to magnetic valve 42 is switched off, magneticvalve 42 opens, and triggers, through the relief of hydraulic workingchamber 20, the closing process of gas exchange valve 10 by valveclosing spring 21.

The operation of the control device is as follows:

Upon rotation of camshaft 25, pump plunger 22 is driven by cam 26 toexecute a continuous back-and-forth stroke motion, such that when thereis a downward-directed stroke motion pump chamber 24 is filled withpressure medium from pressure medium reservoir 39 via pump inlet 36 andpump inlet valve 35. During the upward-directed stroke motion, as soonas lower edge 291 of spool valve 29 closes the lower edge of controlgroove 27, called control edge 271, pressure builds up in pump chamber24. Via pump outlet 38, this pressure is introduced into hydraulicworking chamber 20 of actuator 12, through which control piston 19 isdisplaced against the spring force of valve closing spring 21, and gasexchange valve 10 is opened. If spill opening 30 made in spool valve 29overlaps with control edge 271, this pressure is relieved, through whichthe spill of control-sleeve pump 13 is achieved. After the spill,non-return valve 37 prevents the immediate intake of gas exchange valve10, so that the instantaneous valve stroke is maintained. If now, or atan earlier time, i.e. already during the delivery stroke ofcontrol-sleeve pump 13, the current is shut off to magnetic valve 42,which is closed when supplied with current, then at the desired timereturn line 41 to pressure medium 39 reservoir opens, which triggers animmediate closing of gas exchange valve 10 by valve closing spring 21.

The control device shown in a block diagram in FIG. 3 is modified inrelation to the control device described by FIG. 1 in that thenon-return valve between pump chamber 24 and pump outlet 38 has beenomitted, and return line 41 to pressure medium reservoir 39 is connectedto pump outlet 38 not via an electrically controllable shutoff valve,but rather via a simple pressure limiter or overflow valve 43, whichopens mechanically when there is excess pressure. In this case, incontrast to the case shown in FIG. 1 with magnetic valve 42, a variablestroke cannot be controlled, but the opening and closing time, i.e. theduration and phase position of the opening of gas exchange valve 10,can, as described, be varied via the axial displacement of spool valve29 and the rotation of pump plunger 22. In other respects, the exemplaryembodiment according to FIG. 3 corresponds to the exemplary embodimentaccording to FIG. 1, so that identical components have been providedwith identical reference characters.

In the case of gas exchange valves 10, an actuator 12 is allocated toeach gas exchange valve 10, and actuators 12 can be connected to acommon control-sleeve pump 13 by selected gas exchange valves 10situated in various combustion cylinders 11. A precondition of this isthat the opening times of the various gas exchange valves 10 do notoverlap.

As is shown in the exemplary embodiment according to FIG. 4 of thecontrol device for two gas exchange valves 10 situated in differentcombustion cylinders, an actuator 12 is allocated to each gas exchangevalve 10, and in addition a switchover valve 44 is provided that has twovalve outlets 442, 443 and has a valve inlet 441 that can optionally beconnected with valve outlets 442, 443. In the exemplary embodiment shownin FIG. 4, switchover valve 44 is formed as a 3/2-way magnetic valve 45having a spring return mechanism. An hydraulic working chamber 20 of anactuator 12 is connected with a respective valve output 442 or 443,while valve inlet 441 is adjacent to pump outlet 38. In therepresentation shown in FIG. 4, the upward motion of pump plunger 22 ofcontrol-sleeve pump 13 in its pump chamber 24 results in the buildup ofa high pressure that has been introduced into hydraulic working chamber20 of actuator 12 (shown at the left in FIG. 4) due to the switchingposition of switchover valve 44, and has resulted in an opening motionof valve element 10. Hydraulic working chamber 20 of actuator 12 (shownat right in FIG. 4) is shut off by switchover valve 44 and is withoutpressure, so that gas exchange valve 10 (at the right in FIG. 4) is inits closed position. For the controlling of gas exchange valve 10 (atthe right in FIG. 4), switchover valve 44 is to be switched over, whichrepresents only a small demand in terms of switching time. In otherrespects, the design and manner of operation of the control deviceaccording to FIG. 4 correspond to those shown in FIG. 1, so thatidentical components have been provided with identical referencecharacters.

The invention is not limited to the exemplary embodiment describedabove. Thus, the rotational movability of pump plunger 22 can beomitted, and instead spool valve 29 can have, in addition to itscapacity for axial displacement, a rotational controlling. The situationof control groove 27 and spill opening 30 in pump plunger 22 and spoolvalve 29 can be exchanged.

1. A device for controlling at least one gas exchange valve allocated toa combustion cylinder of an internal combustion engine, comprising: ahydraulic actuator for performing a valve actuation; and a high-pressurepump that charges the hydraulic actuator with a pressure medium underhigh pressure, wherein: the high-pressure pump includes a control-sleevepump provided with a pump plunger that executes a stroke motion and thatlimits a pump chamber, the high-pressure pump includes a spool valvethat surrounds the pump plunger, one of the pump plunger and the spoolvalve includes a control groove that runs obliquely to a strokedirection of the pump plunger, another one of the pump plunger and thespool valve includes a spill opening that works together with thecontrol groove so that when the spill opening and the control grooveoverlap, a relief of pressure of the pump chamber is achieved, the pumpplunger and the spool valve are able to be rotated relative to oneanother, and the spool valve is able to be displaced relative to thepump plunger, for a controlling of a phase position and a duration of anactivation of the at least one gas exchange valve through an activationand deactivation of the hydraulic actuator.
 2. The device as recited inclaim 1, wherein: the control groove is incorporated in a jacket of thepump plunger and is connected with the pump chamber via a connectingbore that runs in the pump plunger, and the spill opening is situated inthe spool valve and is formed as a radial bore.
 3. The device as recitedin claim 1, further comprising: a pressure medium reservoir connected toa pump inlet of the pump chamber; and a pump inlet valve situatedbetween the pump chamber and the pump inlet, wherein: the pump chamberincludes a pump outlet connected with the hydraulic actuator.
 4. Thedevice as recited in claim 3, wherein: the pump inlet valve includes anon-return valve.
 5. The device as recited in claim 3, wherein: thehydraulic actuator includes a control piston that is coupled with the atleast one gas exchange valve, that limits a hydraulic working chamber,and that is able to be displaced against a valve closing spring by thepressure medium introduced into the hydraulic working chamber, and thehydraulic working chamber is connected to the pump outlet.
 6. The deviceas recited in claim 3, further comprising: a cam shaft; and a camsituated on the cam shaft, wherein: the pump plunger is driven toexecute the stroke motion via the cam.
 7. The device as recited in claim3, further comprising: a pressure limiting valve connected to the pumpoutlet.
 8. The device as recited in claim 3, further comprising: anon-return valve situated between the pump chamber and the pump outlet;and an electrically controllable shutoff valve, wherein: a reliefopening that is able to be closed optionally by the electricallycontrollable shutoff valve is connected to the pump outlet.
 9. Thedevice as recited in claim 8, wherein: the electrically controllableshutoff valve includes a 2/2-way magnetic valve having a spring returnmechanism.
 10. The device as recited in claim 9, further comprising: areturn line that leads to the pressure medium reservoir and is connectedto the relief opening.
 11. The device as recited in claim 1, wherein:the pump plunger is rotatable.
 12. A device for controlling a pluralityof gas exchange valves allocated to combustion cylinders of an internalcombustion engine, comprising: a plurality of hydraulic actuators, eachone of the hydraulic actuators being allocated to a respective one ofthe gas exchange valves for performing a valve actuation; and ahigh-pressure pump that charges each hydraulic actuator with a pressuremedium under high pressure, wherein: the high-pressure pump includes acommon control-sleeve pump provided with a pump plunger that executes astroke motion and that limits a pump chamber, the common control-sleevepump being connected to the hydraulic actuators, the high-pressure pumpincludes a spool valve that surrounds the pump plunger, one of the pumpplunger and the spool valve includes a control groove that runsobliquely to a stroke direction of the pump plunger, another one of thepump plunger and the spool valve includes a spill opening that workstogether with the control groove so that when the spill opening and thecontrol groove overlap, a relief of pressure of the pump chamber isachieved, the pump plunger and the spool valve are able to be rotatedrelative to one another, and the spool valve is able to be displacedrelative to the pump plunger, for a controlling of a phase position anda duration of an activation of the gas exchange valves through anactivation and deactivation of each hydraulic actuator.
 13. The deviceas recited in claim 12, further comprising: a switchover valve forconnecting the hydraulic actuators to the common control-sleeve pump,wherein: the switchover valve includes a valve inlet that is able to beconnected optionally with two valve outlets, one of the hydraulicactuators is connected with each of the two valve outlets, and the valveinlet is adjacent to a pump outlet of the pump chamber.
 14. The deviceas recited in claim 13, wherein: the switchover valve includes a 3/2-waymagnetic valve having a spring return mechanism.
 15. The device asrecited in claim 12, wherein: the pump plunger is rotatable.